You can't imagine how much i wanted to like this movie, but the truth is that it is actually terrible, and even worse if you compare it with the first one. They've turned what could've been a magnificent movie in some sort of generic comedy that tries really hard to be a serious movie.
Horrible, ridiculous script ("We should drink to Scotland").
Awkward situations, like when the princess is hanging out with Eggsy and his friends, who act and look like tramps. Why is she even there? She's a princess, dammit! Does she even like those people? They could've shot the scene without her and there'd be no difference.
Moronic, nonsensical characters (Poppy and the president, for instance).
Great actors, yet horrible performances (Colin Firth, Mark Strong).
Tatum's character (Tequila) is just useless, he literally appears a couple of times in the movie and then he gets poisoned. Contributes nothing to the plot.
Also, the Kingsman were supposed to be the best of the best, but even though, agent Tequila, an agent from the Statesman, seems to beat two Kingsman agents at the same time without even blinking.
Scary Movie-like "humor" (agent Whiskey, while fighting some crazy idiots in a bar, throws one of the guys against a table that's right behind where Harry is sitting as the camera focuses on how he keeps talking to Merlin and Eggsy like nothing happened).
Very bad CGI. I don't even need to explain this here, if you watch the movie, you'll see what am i talking about.
Situations that add nothing to the plot (Merlin, who has never shown interest in music whatsoever, out of the blue, decides that he likes John Denver, which is nothing but a lame excuse to show him singing "Country Roads" before he dies, in an attempt to make the scene somehow "epic").
There are a lot more of details that make this movie bad, but these are the ones which bugged me the most.
Even though, this movie is worth a watch if you liked the first one and you want to keep up with Kingsman's storyline.